Adaptive gas analyzer

Abstract

A gas-phase chemical analyzer has at least one gas chromatography column in gas-flow communication with at least one gas carrying tube of an optical absorption cell, a laser for illuminating molecules in a gas mixture flowing though the at least one gas carrying tube of the optical absorption cell, and a photodetector or photodetecting apparatus for measuring absorption spectra of the gas mixture illuminated by the laser. A first module is provided for statically identifying particular molecules in the gas mixture from other molecules in said gas mixture and a second module is provided for comparing at least selected ones of the particular molecules in the gas mixture with a reference library of absorption spectra of previously identified molecules and for determining the likelihood of a correct identification of the particular molecules in the gas mixture and the previously identified molecules in the reference library.

What is claimed is: 
     
       1. A gas-phase chemical analyzer comprising a plurality of gas chromatography columns in gas-flow communication with an gas flow input of at least one gas carrying tube of an optical absorption cell, a recirculation path for routing a gas flowing from said optical absorption cell to another gas chromatography column, a laser for illuminating molecules in a gas mixture flowing though said at least one gas carrying tube of the optical absorption cell, a photodetecting apparatus for measuring absorption spectra of the gas mixture illuminated by said laser, a first module which implements an Independent Component Analysis (ICA) algorithm for statically distinguishing, based on the measured absorption spectra, particular molecules in said gas mixture from other molecules in said gas mixture and a second module which implements a Sparse Reconstruction and Classification (SRC) algorithm for comparing spectra for at least selected ones of the particular molecules in said gas mixture with a reference library of absorption spectra of previously identified molecules and for determining the likelihood of a correct identification of the particular molecules in said gas mixture and the previously identified molecules in said reference library, wherein the Independent Component Analysis (ICA) algorithm and the Sparse Reconstruction and Classification (SRC) algorithm are implemented in software executing, in use, on a computing device. 
     
     
       2. The gas-phase chemical analyzer of  claim 1  further including at least one gas flow controller for controlling how the gas mixture flows from the one gas chromatography column to the another gas chromatography column and whether the gas mixture flows to the at least one gas carrying tube of the optical absorption cell before or after flowing to the another gas chromatography column. 
     
     
       3. The gas-phase chemical analyzer of  claim 2  wherein the at least one gas flow controller is responsive at least in part to the likelihood of a correct identification of the particular molecules in said gas mixture as determined by said second module. 
     
     
       4. The gas-phase chemical analyzer of  claim 2  wherein the computing device is a microprocessor. 
     
     
       5. The gas-phase chemical analyzer of  claim 2 , wherein the laser is a wavelength scanning long wave infrared (LWIR) laser and the photodetecting apparatus comprises a LWIR photodetector formed of either HgCdTe material or an InAs/GaSb superlattice. 
     
     
       6. The gas-phase chemical analyzer of  claim 2 , wherein the laser is a wavelength scanning long wave infrared (LWIR) laser and the photodetecting apparatus comprises a LWIR to short wave infrared (SWIR) upconverting cavity and a SWIR photodetector. 
     
     
       7. The gas-phase chemical analyzer of  claim 6 , wherein the LWIR to SWIR upconverting cavity comprises non-linear optical quasi-phase-matching (QPM) piece or crystal which is responsive to LWIR light from the optical absorption cell and to light from a wavelength scanning SWIR pump laser. 
     
     
       8. A gas-phase chemical analyzer comprising a computing device, first and second first gas chromatography columns in gas-flow communication with a gas flow input of an optical absorption cell, an arrangement of valves in gas-flow communication with a gas flow output of the optical absorption cell and in gas flow communication with gas flow inputs of said first and second gas chromatography columns, at least one gas flow controller for selecting whether the gas mixture flowing via said arrangement of valves from the optical absorption cell flows to the gas flow input of said first gas chromatography column or to the gas flow input of second gas chromatography column or to both the gas flow inputs of said first and second gas chromatography columns, a laser for illuminating molecules in at least one gas mixture flowing, in use, though said optical absorption cell and a photodetecting apparatus for detecting absorption spectra of the at least one gas mixture illuminated, in use, by said laser, said laser being a long wave infrared (LWIR) laser, the computing device receiving detected absorption spectra from the photodetecting apparatus, the photodetecting apparatus including a short wave infrared (SWIR) photodetector and a LWIR to SWIR upconverting cavity, the upconverting cavity including a non-linear optical quasi-phase-matching (QPM) piece or crystal and a wavelength scanning SWIR pump laser, the QPM piece or crystal being responsive to LWIR light from the optical absorption cell and to light from said wavelength scanning SWIR pump laser, the at least one gas flow controller being controlled, in use, by said computing device for controlling which one of said first and second as chromatography columns receives the gas mixture in response to said detected absorption spectra. 
     
     
       9. The gas-phase chemical analyzer of  claim 8  further including at least one additional gas flow controller for controlling how the gas mixture flows from a gas flow output of a selected one of said first and second gas chromatography columns to a gas flow input of the optical absorption cell, the at least one additional gas flow controller being controlled by said computing device. 
     
     
       10. The gas-phase chemical analyzer of  claim 9  wherein the at least one gas flow controller and the at least one additional gas flow controller cooperate under control of said computing device to control whether the gas mixture flows to a selected one of said first and second gas chromatography columns after flowing to another selected one of said first and second gas chromatography columns via said optical absorption cell. 
     
     
       11. The gas-phase chemical analyzer of  claim 8  further including a software first module executing, in use, on said computing device for statically distinguishing spectra for particular molecules in said gas mixture from spectra for other molecules in said gas mixture and a software second module executing, in use, on said computing device for comparing at least selected ones of the spectra for particular molecules in said gas mixture with a reference library of absorption spectra of previously identified molecules and for determining the likelihood of a correct identification of the particular molecules in said gas mixture from the previously identified molecules in said reference library, said computing device selecting said selected one of said first and second gas chromatography columns in response thereto. 
     
     
       12. The gas-phase chemical analyzer of  claim 8  wherein at least one gas flow controller, in use, selecting whether the gas mixture flowing from a gas flow output of the optical absorption cell flows to the gas flow input of said first gas chromatography column or to the gas flow input of second gas chromatography column or to both the gas flow inputs of said first and second gas chromatography columns. 
     
     
       13. A gas-phase chemical analyzer comprising a computing device, at least one gas chromatography column in gas-flow communication with at least one gas carrying tube of an optical absorption cell, a laser for illuminating molecules in a gas mixture flowing though said at least one gas carrying tube of the optical absorption cell, a photodetecting apparatus for measuring absorption spectra of the gas mixture illuminated by said laser, the laser being a wavelength scanning long wave infrared (LWIR) laser, wherein said at least one gas chromatography column comprises a plurality of gas chromatography columns connected gas-flow wise in series with the at least one gas carrying tube of the optical absorption cell and further including at least one gas flow controller for controlling how the gas mixture flows from one gas chromatography column to another gas chromatography column via said optical absorption cell, the at least one gas flow controller controls, in response to said computing device, whether the gas mixture flows to the at least one gas carrying tube of the optical absorption cell either before or after flowing to said another gas chromatography column, the computing device receiving detected absorption spectra from the photodetecting apparatus, the photodetecting apparatus including a LWIR to short wave infrared (SWIR) upconverting cavity and a SWIR photodetector, the LWIR to SWIR upconverting cavity including a non-linear optical quasi-phase-matching (QPM) piece or crystal which is responsive to LWIR light from the optical absorption cell and a wavelength scanning SWIR pump laser, the at least one gas flow controller being controlled, in use, by said computing device for controlling how the gas mixture flows from said one gas chromatography column to said another gas chromatography column and also via said optical absorption cell. 
     
     
       14. A gas-phase chemical analyzer comprising a computing device, first and second first gas chromatography columns in gas-flow communication with a gas flow input of an optical absorption cell, an arrangement of valves in gas-flow communication with a gas flow output of the optical absorption cell and in gas flow communication with gas flow inputs of said first and second gas chromatography columns, at least one gas flow controller for selecting whether the gas mixture flowing via said arrangement of valves from the optical absorption cell flows to the gas flow input of said first gas chromatography column or to the gas flow input of second gas chromatography column or to both the gas flow inputs of said first and second gas chromatography columns, a laser for illuminating molecules in at least one gas mixture flowing, in use, though said optical absorption cell and a photodetecting apparatus for detecting absorption spectra of the at least one gas mixture illuminated, in use, by said laser, the computing device receiving detected absorption spectra from the photodetecting apparatus, the at least one gas flow controller being controlled, in use, by said computing device for controlling which one of said first and second as chromatography columns receives the gas mixture in response to said detected absorption spectra and further including a sampler/concentrator for collecting and concentrating a mixture of analytes and injecting that mixture as a temporal pulse into one of said first and second gas chromatography columns, the first and second gas chromatography columns having different coating materials whereby molecules of different chemical species in said mixture of analytes adhere to and are retained by the first and second first gas chromatography columns for differing periods of time, the first and second gas chromatography columns outputting, in use, streams of gas-phase temporal pulses into the absorption cell, with at least some of those pulses comprising different mixtures of time-wise separated compounds from said analytes. 
     
     
       15. The gas-phase chemical analyzer of  claim 14  further including a software first module executing, in use, on said computing device for generating multiple demixed spectra, each of said multiple demixed spectra being associated with different mixtures of time-wise separated compounds from said analytes. 
     
     
       16. The gas phase chemical analyzer of  claim 15  further including a software second module executing, in use, on said computing device for reconstructing said each of said multiple demixed spectra as a weighted combination of selected reference spectra that are stored in a reference library. 
     
     
       17. The gas phase chemical analyzer of  claim 16  wherein said software second module executes, in use, on said computing device for selecting a first subset of reference spectra from the reference library to be considered for analysis of a demixed spectrum at a first time and a second subset of reference spectra from the reference library to be considered for analysis of a demixed spectrum at a second time. 
     
     
       18. A gas-phase chemical analyzer comprising a computing device, plurality of gas chromatography columns in gas-flow communication with a gas flow input of at least one optical absorption cell, at least one gas flow controller for selectively routing gas flowing from said at least one optical absorption cell to a gas flow input of another one or ones of said plurality of gas chromatography columns, a laser for illuminating molecules in at least one gas mixture flowing, in use, though said optical absorption cell and a photodetecting apparatus for detecting absorption spectra of the at least one gas mixture illuminated, in use, by said laser, the computing device, in use, receiving said absorption spectra of the at least one gas mixture illuminated, the at least one gas flow controller being controlled, in use, by said computing device and further including a sampler/concentrator for collecting and concentrating a mixture of analytes and injecting that mixture as a temporal pulse into one of said plurality of gas chromatography columns, said one and at least another one of gas chromatography columns having different coating materials whereby molecules of different chemical species in said mixture adhere to and are retained by said one and said at least another one of said plurality of gas chromatography columns for differing periods of time, said one and said at least another one of said plurality of gas chromatography columns outputting, in use, streams of gas-phase temporal pulses into the at least one absorption cell, with at least some of those pulses comprising different mixtures of time-wise separated compounds from said analytes. 
     
     
       19. The gas-phase chemical analyzer of  claim 18  further including a software first module executing, in use, on said computing device for generating multiple demixed spectra, each of said multiple demixed spectra being associated with different mixtures of time-wise separated compounds from said analytes. 
     
     
       20. The gas phase chemical analyzer of  claim 19  further including a software second module executing, in use, on said computing device for reconstructing said each of said multiple demixed spectra as a weighted combination of selected reference spectra that are stored in a reference library. 
     
     
       21. The gas phase chemical analyzer of  claim 20  wherein said software second module executes, in use, on said computing device for selecting a first subset of reference spectra from the reference library to be considered for analysis of a demixed spectrum at a first time and a second subset of reference spectra from the reference library to be considered for analysis of a demixed spectrum at a second time.